Coating suitable for surgical instruments

ABSTRACT

A coating and devices using the coating are provided. The coating is applied in liquid form and dried or otherwise cured to form a durable adherent coating resistant to high temperatures and having optional hydrophobic properties. The coating formulation contains an aqueous formulation of silica, one or more fillers, and sufficient base, (e.g., potassium hydroxide), to have a pH exceeding about 10.5 during at least part of the formulation process. The formulation may contain a compound(s) that affects surface free energy, energy to make the cured coating hydrophobic. Such compounds include silanes containing halogens (e.g., fluorine or chlorine) and in particular silanes containing one or more hydrolyzable groups attached to at least one silicon atom and a group containing one or more halogens (e.g., chlorine or fluorine). A medical instrument (e.g., electrosurgical instrument) may be at least partially covered by a coating using the formulation.

RELATED APPLICATIONS

This is a continuation of U.S. patent application Ser. No. 12/768,962filed Apr. 28, 2010, entitled “COATING SUITABLE FOR SURGICALINSTRUMENTS,” which application claimed priority to U.S. patentapplication Ser. No. 11/627,340 filed Jan. 25, 2007, entitled “COATINGSUITABLE FOR SURGICAL INSTRUMENTS,” which application claimed priorityto U.S. Provisional Patent Application No. 60/762,375 filed Jan. 25,2006, entitled “COATING FOR SURGICAL INSTRUMENTS AND RELATED METHODS ANDAPPARATUS,” each of which applications are incorporated herein byreference in their entirety.

FIELD OF THE INVENTION

The present invention relates to materials' coatings and using coatingsto protect and affect the surface properties of products or apparatus atleast partially covered with such coatings, such as instruments usedduring surgical procedures. The invention may be used in applicationswhere coatings are useful and more particularly for applicationsbenefiting from containing one or components containing materialsbenefiting from protecting the component from the use environment or theuse environment from the component. Examples of such protection areprotecting components from high temperatures, liquids or vapors, such asmoisture or steam, or protecting materials in the use environment fromhigh temperature components. The invention is advantageous where anadherent coating able to withstand high temperatures, such as a coatingbeing adherent to metals, protects components from the use environmentor protects elements of the use environment from components. An exampleof such use is on instruments that apply electrosurgical power to atissue site to achieve a predetermined surgical effect. Another exampleof such use is coating engine exhaust components such as mufflers.Another example of such use is coating doors to improve thermal oroxidative resistance, such as fire doors. Aspects of the presentinvention include a composition for coating formulation, a method forpreparing the composition, and a method for forming a coating using thecomposition.

BACKGROUND OF THE INVENTION

Electrical energy is widely employed during surgical procedures in whichelectrosurgical techniques are employed to provide localized high fluxenergy to tissue during open, laparoscopic, and arthroscopicapplications to provide clinical benefits, such as hemostasis, relativeto surgical approaches that use mechanical cutting such as scalpels.Electrosurgical techniques typically entail the use of a hand-heldinstrument, or pencil, that transfers alternating current electricalpower operating at radio frequency (RF) to tissue at the surgical site.The time-varying RF electrical power yields a predeterminedelectrosurgical effect, such as tissue cutting or coagulation.

The process of applying RF electrical power causes high temperatures tooccur in the tissue and on at least part of the surgical instrument. Theresult of these high temperatures is the formation of tissue fragmentsand other substances that often accumulate and form deposits on surgicalinstruments. These deposits are called eschar. Eschar frequentlyaccumulates in such amounts that it interferes with surgical procedures.

In attempts to alleviate the formation of eschar or make instrumentsfrom which eschar may be more easily removed than from metal surfaces,instruments with surface coatings, such as coated blades, have been usedor described. For example, such coatings are made from materials towhich eschar accumulations stick less tightly than they stick to themetals from which electrosurgical instruments are made. The coatings aretypically made from one or more polydiorganosiloxane orpolytetrafluorethylene (PTFE) compounds. These compounds suffer from nothaving high temperature durability. Materials capable of withstandinghigh temperatures, such as ceramics, do not confer adequate non-stickproperties when used as coatings. In this regard, the present inventorshave recognized that the need exists for a high temperature coating thathas non-stick properties.

Relatedly, the metal conductors in electrosurgical instruments thatconvey energy to tissue get hot during use. When contacting tissue thehot surfaces damage tissue. Therefore, protecting tissue in the useenvironment from the hot instrument surfaces can reduce tissue damage.Typical coatings cannot withstand the high temperatures in regionsdirectly adjacent to where RF electrical power transfers to tissue. Inthis regard, the present inventors have also recognized that the needexists for a high temperature coating with insulating properties.

In general, the present inventors believe that the need exists for acoating that can protect component materials from the use environmentand the use environment from components.

SUMMARY OF THE INVENTION

Accordingly, an objective of the present invention is to provide acoating formulation, method for preparing the coating formulation, andmethod for applying the coating formulation to one or more components inan apparatus that needs protection from the use environment or thatneeds to have the use environment protected from the apparatus.

An objective of the present invention is to provide a coatingformulation, method for preparing the coating formulation, and methodfor applying the coating formulation to one or more components ofdevices used in surgical environments.

An objective of the present invention is to provide a coatingformulation, method for preparing the coating formulation, and methodfor applying the coating formulation to one or more components ofdevices used in surgical environments that results in a durable hightemperature nonstick coating.

Another objective of the present invention is to provide a coatingformulation, method for preparing the coating formulation, and methodfor applying the coating formulation to a surgical instrument powered byelectrosurgical energy that results in reduced eschar accumulation.

In addressing these objectives, the present inventors have recognizedthat a novel coating formulation containing silica (e.g., colloidaland/or amorphous silica), inorganic fillers, and a strong base such thatthe pH of the formulation exceeds 10.5 during at least part of thepreparation process produces a durable adherent high temperature coatingto which a treatment such as a non-stick outer coating may be applied.In this regard, the use of a strong base advantageously serves to atleast partially dissolve the silica.

In one aspect, the present inventors have further recognized that anovel coating containing silica (e.g., colloidal and/or amorphoussilica), inorganic fillers, and a strong base such that the pH of theformulation exceeds 10.5 during at least part of the preparationprocess, and which additional constituents such as alkoxy silanes may beadded, produces a coating that is inherently non-stick, adherent,durable, and capable of withstanding high temperatures. The presentinventors have further recognized that such coatings have non-stickproperties when the formulation contains one or more halogen-containingalkylalkoxysilanes, e.g., those containing halogens such as fluorine orchlorine. In the latter regard, and by way of example,fluoroalkylalkoxysilanes or chloroalkylalkoxysilanes may be employed.

The present inventors have yet further recognized that such use ofalkylalkoxysilanes possessing hydrolyzable inorganic alkylsilyl groupsincluding methoxysilyl or ethoxysilyl groups produces durable hightemperature coatings. The present inventors have yet further recognizedthat using alkylalkoxysilanes possessing hydrolyzable inorganicalkylsilyl groups including methoxysilyl or ethoxysilyl groups and oneor more straight or branched halogenalkyl chains, such as chloroalkyl orfluoroalkyl chains, produces durable high temperature coatings withexcellent hydrophobic and oleophobic (non-stick) properties.

The present inventors have yet further recognized that a coatingcontaining silica (e.g., colloidal and/or amorphous silica), inorganicfillers, and a strong base such that the pH of the formulation exceeds10.5 during at least part of the formulation process to which one ormore substance containing one or more fluorinated carbon chains, such asPTFE emulsions or at least partially hydrolyzed fluorinated silanes orat least partially cross-linked hydrolyzed silanes, form a coating thatis inherently non-stick, adherent, durable, and capable of withstandinghigh temperatures.

In another aspect, the present inventors have further recognized thatadding materials such as water, surfactants, and solids such as fumedsilica alter the viscosity and surface tension of the formulation toallow it to flow or otherwise cover surfaces producing coatings havingdifferent thicknesses or surface finishes and making coatings suitablefor various application methods such as dipping or spraying.

In further addressing the objectives of the present invention theinventors have recognized that the coating formulation of the presentinvention may be applied to organic and inorganic materials, such ascloth, glass, plastic, and metal materials and produce durable adherentcoatings. Such coating may be restricted to the surface or may penetrateinto interstitial pores, cracks, crevices, or other voids that exist.

In further addressing the objectives of the present invention theinventors have recognized that the coating formulation of the presentinvention may be applied to electrically conductive metal surfaces andproduce durable adherent coatings suitable for use on medicalinstruments including instruments suitable for use with electrosurgery.The present inventors have further recognized that the coatingformulation of the present invention may be applied to stainless steeland materials having thermal conductivities greater than stainlesssteel, such as molybdenum, and produce durable adherent coatingssuitable for medical instruments including instruments suitable for usewith electrosurgery. The present inventors have further recognized thatsurgical instruments comprised at least in part with metals havingcoatings based on the formulation of the present invention are mostsuitable for use in electrosurgical applications when at least one partof the metal surface is left uncoated or sufficiently thinly coated sothat an energy transfer path exists with sufficiently low impedance,less than approximately 5,000 ohms, that electrosurgical energy canadequately transfer from the surgical instrument to the tissue where apredetermined surgical effect is desired to occur.

In still further addressing the objectives of the present invention theinventors have recognized that the coating formulation of the presentinvention may be applied by dipping, spraying, painting, printing, padprinting, or other means capable of transferring a liquid substance to asubstrate such as one made from metal or a surgical instrument. In stillfurther addressing the objectives for the present invention theinventors have recognized that the coating formulation of the presentinvention may be applied in multiple coats to build up a final coat. Thepresent inventors have further recognized that such multiple coats maybe applied prior to applying energy to any already applied coat, suchapplication of energy being applied to cure the coating material.

In still further addressing the objectives of the present invention theinventors have recognized that the coating formulation of the presentinvention may be cured by applying energy, such as thermal energytransferred by conduction from air or radiation from one or moresurfaces, to enhance the properties of the coating, such as itsdurability, resistance to moisture, adherence, and non-stick properties.

In short, the present inventors have recognized that a durable coatingis needed to improve the performance of apparatus, such as to prevent orreduce the formation or accumulation of the deposits that form onmaterial surfaces such as the surfaces of surgical instruments poweredby electrosurgical energy. The present invention comprises a coatingformulation that includes colloidal silica, a strong base, one or morefillers, and optionally formulated with one or more substances thatproduce non-stick properties to the coating. Such substance that producenon-stick properties include alkoxy silanes, including alkoxy silaneshaving one or more chains containing at least some halogens such aschlorine or fluorine. The present invention further includes applyingsuch coating formulations to surfaces to produce a coating on materials,including materials with organic or inorganic surfaces, includingplastic, glass, and metallic surfaces, that is adherent, resistant tohigh temperatures, and non-stick. The present invention furthercomprises such metallic surfaces when they are at least part of amedical instrument, such as an electrosurgical instrument.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates one embodiment of a method of preparing inventivecoating formulations in accordance with the present invention.

FIG. 2 illustrates one embodiment of a method of coating a surface of anapparatus coating with an inventive coating formulation prepared inaccordance with the present invention.

FIG. 3 portrays a cross section of a surgical blade with at least partof its surface insulated with a coating.

DETAILED DESCRIPTION

The present invention is for coating formulations capable ofwithstanding high temperatures and adherent to metal surfaces and thatmay be formulated to have a surface free energy that makes the surfacesubstantially non-stick, meaning that the surface is substantiallyhydrophobic or oleophobic, or both. Such coating formulations haveapplicability when used to form a surface coat on surgical instrumentsreceiving electrosurgical energy and contacting tissue to achieve apredetermined surgical effect. The present invention further includesapplying the subject coating formulations and optionally enhancing thecoating's properties by applying energy, such as thermal energy. Thecoating formulation comprises a silicate solution, such as a colloidalsilicate solution, one or more fillers, and a strong base and optionallyincludes one or more materials that reduce the surface free energy toenhance the non-stick properties of the surface.

In one approach, a colloidal silicate solution may contain at least 10weight percent silica. In another embodiment the colloidal silicatesolution may contain about 50 weight percent silica. Representativeexamples of colloidal silicate solutions are alkali metal silicates,including those of lithium polysilicate, sodium silicate, and potassiumsilicate, and colloidal silica. The colloidal silicate solution may becolloidal silica with about 50 weight percent silica. The colloidalsilica average particle size may be between about 5 nm and 100 nm and itmay be between about 30 and 80 nm and it may be between about 40 and 80nm. Example colloidal silica products are Megasol S50 (WesBondCorporation) and LEVASIL® 50/50% (H.C. Starck GmbH).

The coating formulation includes a strong base in a concentration thatcauses the pH of the formulation to exceed 10.5 at least at some pointduring the formulation process. The strong base functions to at leastpartially dissolve the silica. For example, the strong base may be addedin sufficient amount to cause at least the initial pH to exceed 12 andthe strong base may be added to exceed 12.5. The strong base used may bepotassium hydroxide (KOH). The KOH may be added as a KOH solutionconsisting of KOH and water and the concentration of the solution may beapproximately 50 weight percent KOH, or between approximately 20 percentand 80 percent.

The filler material may comprise various metal/non-metal combinations,including, for example, compositions that comprise the following:aluminum oxides (e.g., alumina and Al₂O₃), zirconium oxides (e.g.,Zr₂O₃), zirconium nitrides (e.g., ZrN), zirconium carbides (e.g., ZrC),boron carbides (e.g., B₄C), silicon oxides (e.g., SiO₂), mica,magnesium-zirconium oxides (e.g., (Mg—Zr)O₃), zirconium-silicon oxides(e.g., (Zr—Si)O₂), titanium oxides (e.g., TiO₂) tantalum oxides (e.g.,Ta₂O₅), tantalum nitrides (e.g., TaN), tantalum carbides (e.g., TaC),silicon nitrides (e.g., Si₃N₄), silicon carbides (e.g., SiC), tungstencarbides (e.g., WC) titanium nitrides (e.g., TiN), titanium carbides(e.g., TiC), nibobium nitrides (e.g., NbN), niobium carbides (e.g.,NbC), vanadium nitrides (e.g., VN), vanadium carbides (e.g., VC), andhydroxyapatite (e.g., substances containing compounds such as3Ca₃(PO₄)₂Ca(OH)₂Ca10(PO₄)₆(OH)₂Ca5(OH)(PO₄)₃, and Ca₁₀H₂O₂6P₆).

Filler materials may be of any shape including, for example, shapes thatapproximate in whole or in part or are substantially fibers, plates,spheres, rods, coils, or polyhedrons such as cubes or other shapes thatmay be approximated by a collection of polygons. Combinations of fillermaterials having more than one shape may be used. For example, fillerscomprising one or more materials having fiber shapes and plate-likeshapes may be used.

The filler may have one or more constituents comprising at least in partone or more inorganic fibers or inorganic powders such as those derivedfrom clays with such fillers including those that contain silicon oxide,aluminum oxides, magnesium oxides, titanium oxides, chrome oxides,calcium oxides, or zirconium oxides. The filler materials may containone or more materials that have at least 30 percent by weight Al₂0₃ orSi0₂ either alone or combined with other elements, such as occurs inkaolin, talc, or montmorillonite. Clays used may include substances thatare members of the smectite group of phyllosilicate minerals.Representative examples of clay minerals include bentonite, talc, kaolin(kaolinite), mica, clay, sericite, hectorite, montmorillonite andsmectite. In the present invention, at least one of kaolin, talc, andmontmorillonite may be used. These clay minerals can be used singly orin combination.

The filler may have one or more constituents that are at least in partfibers that contain in part or wholly alumina or silica or calciumsilicate, such as Wollastonite, alumina fiber, silica fiber or fiberscontaining a combination of alumina and silica.

At least one dimension, such as diameter, length, width, or particlesize, of at least one of the filler materials may have a mean value ofless than about 200 micrometers. The materials may have one or morematerial with one or more dimensions with a mean value of less thanabout 50 micrometers. The materials may have one or more dimensions withone or more mean values less than about 10 microns. The materials mayhave one or more dimensions with one or more mean values less than about5 microns, such as both the diameter and thickness being less than about5 microns.

When montmorillonite is used as a filler it may be a form that isuntreated or it may be a form that has been treated with a surfacemodifying process, such as a treatment to enhance its dispersion. Whenused, montmorillonite may be a form that has been onium ion treated. Anexample onium ion treated montmorillonite is Nanomer® I.44P (Nanocor,Inc.).

The filler may include at least in part one or more fibers with meandiameters of between about 1 and 50 μm and it may at least in partinclude one or more fibers with mean diameters of between about 1 and 20μm. Example fibers include RF 50/99 and RF 20/99 (Saint-Gobain™ K.K) andNyglos 2 and Nyglos 4W (Nyco Minerals, Inc.). The filler may include atleast in part a fiber containing Al₂O₃ and SiO₂ in about equal weightpercentage amounts.

Substances may be added to promote adhesion or production of a sealed orhydrophobic surface, including substances that increase the pH of themixture as noted above, including sodium hydroxide or potassiumhydroxide, and hydrolyzable silanes that condense to form one or morecross-linked silicone-oxygen-silicon structures (siloxane bonds).Example materials are those that use one or more of the aforementionedcolloidal silicates and clays, potassium hydroxide, and also use one ormore substances that reduce the surface free energy of the surface. Suchsubstances that reduce the surface free energy include halogenatedcompounds and fluoropolymer compounds, such as PTFE and PFA, includingaqueous dispersions of such compounds, organofunctional hydrolyzablesilanes, including those containing one or more fluorine atoms on one ormore pendant carbon chains.

Among the substances that may be included in the coating material as oneor more hydrolyzable silanes are components having the general formulaR_(m)SiX_(n) where R is alkyl chain and X is hydrolyzable, such a alkoxygroup with m and n both integers and m+n=4. The hydrolyzable silane Rmay contain one or more halogen atoms. The hydrolyzable silane R mayhave a general formula of CF₃(CF₂)_(p)(CH₂)_(q)Si(OCH₂CH₃)₃ where p isless than about 20 and may about 8 or less and where q is about 2. Othergroups besides (OCH₂CH₃)₃, such as those based on methyl, propyl, orbutyl groups, may be substituted and fall within the new art of thispatent when they also are hydrolyzable. Other halogens, such aschlorine, may be substituted for the fluorine.

An example fluoroalkylalkoxysilane istridecafluor-1,1,2,2,-tetrahydrooctyltriethoxysilane. An example of sucha silane is Dynasylan F8261 (Degussa Corp.).

The final coating produced may have a surface free energy (also referredto as the surface tension) of the coating is less than about 32millinewtons/meter and may have a surface free energy less than about 25millinewtons/meter and may have a surface free energy less than about 15millinewtons/meter and may be less than about 10 millinewtons/meter.

The coating formulation may have materials added to modify its viscosityor surface tension. Examples of such materials are amorphous silica,such as in powder form. An example amorphous silica is fumed silica andprecipitated silica. An example amorphous silica is CAB-O-SIL® HS-5(Cabot Corporation). Surfactants may also be added to modify theviscosity or surface tension of the formulation.

The coating formulation may include amorphous silica mixed with a strongbase. The amorphous silica-strong base mixture may be used to augment orreplace some or all of a colloidal silicate material and be mixed withfillers or other materials such as hydrolyzable silanes.

FIG. 1 illustrates one embodiment of a method for preparing coatingformulations in accordance with the present invention. As illustrated,the method of preparation may include the step of combining acombination of silica, an inorganic filler and a base in an amountsufficient to cause the combination to have a pH of at least 10.5 atsome point during the preparation process, step 102. By way of example,the combining step 102 may comprise combining the constituents invarying orders and may include mixing, agitating and/or shaking thecombination one or multiple times. In one approach, colloidal silica, atleast one inorganic filler and potassium hydroxide may be combined. Inanother approach, an amorphous silica such as fumed silica, andpotassium hydroxide may be initially combined, then colloidal silica andan inorganic filler may be added thereto. In yet another approach, thebase may even be added later in the process (e.g., at step 106 or step108, or between steps 106 and 108 noted below). In each approach, thebase (e.g., potassium hydroxide) functions to effectively dissolve atleast a portion of the silica. As further illustrated in FIG. 1, themethod may optionally include the step of combining an alkoxy silaneinto the combination, step 106. As noted above, the additional of analkoxy silane serves to enhance the non-stick properties of the coatingformulation.

As illustrated in FIG. 1, the preparation method may further include theoptional step of combining at least one of water, a surfactant and asolid into the combination, step 108. As previously noted, suchconstituents may be added to enhance the ability of the formulation toflow or otherwise cover surfaces to which the formulation may beapplied. In relation to the optional steps, 106 and 108, the illustratedembodiment may also include the further step of waiting a predeterminedtime period after such step(s), step 110, so as to reduce the viscosityof the combination. In this regard, a waiting period after step 106 mayserve to successively flocculate and peptize the silica. In relation tostep 108, the waiting period may serve to allow for the hydrolization ofsilane alkoxy groups (e.g., when water is combined in step 108). Asnoted in FIG. 1, after step 102 and optional steps 106-110 have beencompleted, the prepared formulation may be utilized to coat an apparatuscomponent such as a metal surface (e.g., an electrosurgical blade).

In this regard, reference will now be made to FIG. 2 which illustratesan exemplary embodiment of a method of coating a surface of at least oneapparatus component with the inventive formulations (e.g., a metalsurface such as an electrosurgical blade). As shown, the method mayinclude the steps of applying the coating formulation to the apparatuscomponent surface, step 202, and drying the applied coating formulationon the apparatus component surface, step 204. The applying step 202 maybe completed utilizing any of a variety of techniques, including forexample, dipping, spraying, brushing, rolling, printing, etc. Similarlythe drying step 204 may be completed in any manner that may function toremove liquid from the coating formulation so as to yield a dry coatedapparatus component surface. By way of example, such drying step mayinclude the sub-step of exposing the coated apparatus component to apredetermined temperature range sufficient to vaporize or otherwiseremove liquid present in the formulation, and including an elevatedambient temperature for a predetermined time period. As noted, thecoating step 202 and drying step 204 may be optionally repeated a numberof times to desirably build-up the coating layer in increments andthereby enhance coverage and overall performance.

Following the drying step 204, the method may further include the stepof curing the applied coating formulation on the apparatus componentsurface so as to yield a durable, high temperature surface coating, step206. Further, depending upon the constituents used in the formulation,non-stick and other properties may be realized as otherwise describedhereinabove. Of note, while separate drying and curing steps are shownin FIG. 2, it should be realized that an extended drying time periodwill also serve to cure the inventive formulations. As such, overlap mayoccur between the drying and curing stages of the process.

An example coating formulation, in weight percent, is

Silica (from colloidal silica) 20-30 Filler 15-30 KOH 8.5-10  Water(from colloidal silica and KOH solution) 35-50 Fluorinated Silane0.25-5  A more specific example formulation is

Component Mass (gm) % Colloidal silica (Levasil 50/50) 56.2 55.3Silica/Alumina fiber (RF 20/99) 7.1 7.0 Montmorillonite (Nanomer I.44P)16.5 16.2 KOH (51 weight percent) 18.8 18.5 Fluorinated silane (F8261)2.3 2.3 Fumed silica (HS-5) 0.75 0.74

For example, the colloidal silica, filler, and KOH solution are combinedand mixed by shaking for one minute. The fluorinated silane is thenadded and the mixture shaken 15 minutes. After shaking, wait 12 hours.During this period the mixture will become less viscous as theflocculated silica peptizes and the silane alkoxy groups hydrolyze. Addthe fumed silica and shake five minutes. Wait one hour. The mixture maythen be applied by dipping, spraying brushing, printing, or other means.

The coating may be applied using any means that conveys a liquid to theobject to which the coating is to be applied. Such methods includespraying, dipping, brushing, rolling, pad printing and printing. Morethan one coat may be applied, such as within 5 seconds and 4 hours ofwhen previous coats were applied or within 5 seconds and 10 minutes ofwhen previous coats were applied.

The coated article may be allowed to air dry at between about 60 and 200degrees Fahrenheit for between about 1 and 8 hours and then cured atbetween about 350 and 500 degrees Fahrenheit for between about 15minutes and one hour. The final cure temperature may be between about400 to 475 degrees Fahrenheit. To reduce bubble formation during curingthe temperature may be ramped between an air dry temperature and thefinal cure temperature such as, for example, over an interval of betweenabout one and eight hours or over about three to six hours. The finalcure may be immediately after air drying or it may be delayed.

A coated article may be a substantially organic surface such as cloth orwood to which the coating is applied and allowed to dry. For materialsthat cannot withstand high temperatures a cure temperature less than thetemperature that damages the material may be used, such as 350 degrees,although longer cure times will be required than when highertemperatures are used.

A coated article may be a metal part, such as a component of an exhaustsystem, that needs to withstand temperatures exceeding, for example, 450degrees Fahrenheit. The coated article may be a metal surface thatbenefits from having non-stick or reduced-stick properties, such ascookware or oven coatings. Such surfaces can be made from, for example,metal or glass. The coating may be applied to a glass surface to improveits non-stick properties. Articles may be coated to provide improvedproperties during elevated temperature service including temperaturesover 450 degrees Fahrenheit. The coating may be applied articlesexpected to experience temperatures exceeding 600 degrees Fahrenheit,such as the surfaces near the edges of electrosurgical instruments wheretemperatures are believed to exceed 600 degrees Fahrenheit and mayexceed 1,000 degrees Fahrenheit.

FIG. 3 illustrates the cross section of an electrosurgical instrument,in this case an electrosurgical blade, that has been at least partiallycoated. The preferred thickness of the coating using the formulation ofthe present invention is between about 0.001 and 0.1 inches and morepreferably between about 0.002 and 0.010 inches. Preferably, at leastpart of the blade is left uncoated or with a coating that leads to animpedance less than about 5,000 ohms so that transfer of electricalenergy is facilitated between the electrosurgical instrument and thetissue, such as when a very thin edge is exposed through the insulation.The blade body 1 is surrounded by insulation 2, defined by the inventivecoating except for at least a portion of the peripheral edge. The lengthof the body extends into the page in this figure.

Various additional embodiments and modifications may be apparent tothose skilled in the art and are within the scope of the presentinvention as defined by the claims which follow.

1. A surgical instrument for receiving electrosurgical energy, whereinat least part of said instrument is insulated with a coating having asubstantially non-stick coating formulation comprising: silica; at leastone inorganic filler; and a base in an amount so that the coatingformulation has a pH of at least 10.5 during at least part of aformulation process, wherein said base comprises potassium hydroxide. 2.The surgical instrument of claim 1, wherein the instrument is a blade.3. The surgical instrument of claim 2 in which the coating is betweenabout 0.001 and 0.1 inches thick.
 4. The surgical instrument of claim 3in which the coating is between about 0.002 and 0.010 inches thick. 5.The surgical instrument of claim 2 in which a portion of the blade hasan impedance of less than about 5,000 ohms comprised of an edge exposedthrough the insulation.
 6. The surgical instrument of claim 2 wherein atleast a portion of said blade is composed of stainless steel.
 7. Thesurgical instrument of claim 1 in which the instrument has at least aportion with an impedance less than about 5,000 ohms.
 8. The surgicalinstrument of claim 1, the coating formulation further comprising: atleast one alkoxy silane.
 9. The surgical instrument of claim 8, whereinsaid at least one alkoxy silane of the formulation comprises at leastone alkylalkoxysilane.
 10. The surgical instrument of claim 9, whereinsaid at least one alkylalkoxy silane of the formulation includes atleast one halogen being at least one of: chlorine and fluorine.
 11. Thesurgical instrument of claim 10, wherein said at least onealkylalkoxysilane of the coating formulation is selected from a groupconsisting of: fluoroalkylalkoxysilanes; and chloroalkylalkoxysilanes.12. The surgical instrument of claim 1, wherein the coating formulationfurther comprises at least one of the following: a material including afluorinated carbon chain; and a material including at least partiallyhydrolyzed fluorinated silanes; and a material including at leastpartially cross-linked hydrolyzed silanes.
 13. The surgical instrumentof claim 11, wherein said at least one alkylalkoxysilane of the coatingformulation comprises at least one hydrolyzable inorganic alkylsilylgroup.
 14. The surgical instrument of claim 13, wherein saidhydrolyzable inorganic alkylsilyl of the coating formulation group isselected from a group consisting of: a methoxysilyl group; and anethoxysilyl group.
 15. The surgical instrument of claim 1, wherein saidcoating formulation comprises at least 10 weight percent of a solutioncomprising a colloidal silicate.
 16. The surgical instrument of claim15, wherein said solution of the coating formulation comprises an alkalimetal silicate solution.
 17. The surgical instrument of claim 1, whereinsaid coating formulation comprises at least 10 weight percent of asolution comprising a colloidal silicate.
 18. A process of manufacturinga surgical instrument in which a stainless steel blade is coated atleast in part with a material that produces a substantially non-stickcoating, comprising: preparing a coating formulation comprising: silica;at least one inorganic filler; at least one hydrolyzable inorganicalkylsilyl; and a base in an amount so that the coating formulation hasa pH of at least 10.5 during at least part of the preparing step,wherein said base comprises potassium hydroxide; applying the coating toat least a portion of a stainless steel blade of a surgical instrument;drying the coated portion of the stainless steel blade at about 60 to200 degrees Fahrenheit; curing the coated portion of the stainless steelblade at a temperature greater than about 350 degrees Fahrenheit. 19.The process claim 18, wherein said at least one hydrolyzable inorganicalkylsilyl contains at least one halogen.
 20. The process claim 18,wherein said at least one halogen is comprised of at least one of:chlorine; and fluorine.